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VX vibrations from rear

VXW

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Hi guys

I just moved to Australia, and buying a Commodore seemed like the only way to get the full Aussie experience out of the 6 months I'm here! But there are troubles in paradise, and since I don't know any mechanic I can trust on this continent, I hope that you can help me out:)

So, I recently bought a VX Wagon 3.8 aut from a private seller. 2001 model, 190.000 kms. I took it for a test drive, it felt fine and I bought it. However, after the seller had the RWC done, it vibrated badly from the rear (I feel it in my back but not in the steering wheel). The vibrations were noticeable from 20-30 km/h, getting worse until 80-90. At 100-110 km/h I don’t feel it as bad, but I can hear vibrations going through the car in waves. The vibrations seems to be worse when the car is cold and gets marginally better once it warms up. Up to around 70 km/h I feel it most significantly when accelerating.

The seller acknowledged the problem and meant, that it was probably because the mechanic forgot to mark the shaft, when he changed the centre shaft bearing as part of the RWC work. So we took the car to the mechanic and had him check it, but we could see for ourselves that it was marked and assembled as it should be. The mechanic even put in another (new) centre bearing unit, but it didn't solve the problem.

Wheel balancing and alignment decreased vibrations to some extend, but it's still there, and it's driving me crazy. Also tried swapping front/rear wheels to check if it's the tyres causing the problem, but vibrations remain the same. The mechanic seemed unsure what the problem then could be, and his suggestion is to try balancing the tail shaft.

Several other things were replaced as part of RWC according to the receipts. I reckon that these are the ones that could have to do with the driveline:
- 2 x engine mounts
- R/H tie rod end
- R/H end link boot

Before I spend money on balancing the shaft, I thought I would check your opinion. Does the problem I describe sound like something that could have to do with balancing the shaft? Or what else could it be?

I really appriciate your help!
 

notStock

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If this helps, I had a similar story in my VT. I got the tail shaft balanced and replaced both driveshafts, as the CV's had gotten old and stiff. That sorted out my vibrations.
 

Tree cutter

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If it only started vibrating after the center bearing was replaced, then the problem must be somewhere in the tailshaft. I thought i read somewhere that there was a problem with tailshaft alignment on some wagons that needed the centre bearing to be lowered with spacers to stop vibrations.
 

VXW

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Thanks for your replies. I've now had the tail shaft balanced, but apparently it was in perfect balance already. The wheels were also balanced again. Still vibrating. The mechanic then tried swapping the tail shaft with that of a similar model he had in, but it didn't iliminate the vibrations neither. So he swapped it back again.

However, something must have happened along the process, because when I picked up the car the vibrations were only noticable at around 80 km/h, so I was a happy man although the mechanic couldn't explain it. He also says that the drive shafts are ok.

But now, a trip to the Grampions and 700 km later (30 km on dirt road), the vibrations are back at normal. Could it have to do with the tires? The brand is Kinforest, so a pretty cheap brand. The grip is decent though.
 

mdjbags

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I have the same problem and almost identical journey with my vx acclaim. I also replaced the rear gearbox mount (its very easy to do). That helped, but still, the main vibrations continue. Its very annoying as i have a perfectlt running and maintained engine but i cant drive above 90kph without unbearable vibration. Wish i knew what to do.
 

gohrdrgomad

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Thanks for your replies. I've now had the tail shaft balanced, but apparently it was in perfect balance already. The wheels were also balanced again. Still vibrating. The mechanic then tried swapping the tail shaft with that of a similar model he had in, but it didn't iliminate the vibrations neither. So he swapped it back again.

However, something must have happened along the process, because when I picked up the car the vibrations were only noticable at around 80 km/h, so I was a happy man although the mechanic couldn't explain it. He also says that the drive shafts are ok.

But now, a trip to the Grampions and 700 km later (30 km on dirt road), the vibrations are back at normal. Could it have to do with the tires? The brand is Kinforest, so a pretty cheap brand. The grip is decent though.
Firstly look for another mechanic.
 
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